Products are typically packaged with a machine-readable code (e.g., a QR code, a barcode, a data matrix, and other similar codes) that identifies the product. For example, the machine-readable code may include manufacturer identification (ID), a product ID, a product serial number, and so on. However, the machine-readable code cannot provide authentication of the product it is attached to, even when containing a unique serial number, since the code itself is easily copied. That is, there is no way to ascertain whether the machine-readable code being scanned is authentic or an image duplicate. Thus, even where a consumer product is marked with the machine-readable code, the code provides no indication of authenticity of the object.
Many mobile phones and tablets include cameras for capturing pictures. These cameras typically use a CMOS (complementary metal-oxide semiconductor) sensor with an infrared (IR) cut-off filter that is designed to block near-IR photons from reaching the imaging sensor, while passing visible light. The IR cut-off filter prevents IR radiation from distorting images formed from visible radiation. While this results in more natural looking images, conventional mobile devices are therefore unsuitable for detecting fluorescent emission at IR wavelengths without removal of the included IR cut-off filter.
Many phosphors emit visible light when excited by Ultraviolet (UV) light. However, mobile phones cannot generate UV light at the appropriate wavelength and intensity to excite these phosphors. Thus, mobile phones have not been considered suitable for visible light authentication.